The new odds come after Amazon released its short list of 20 cities still in the running for HQ2. The list includes major cities like New York and Los Angeles, as well as smaller markets such as Columbus, Ohio and Indianapolis, Indiana. Three locations in the Washington, D.C. metro area also made the cut.

The chances for Montgomery County, Maryland (8-to-1) also shot up after it made the short list. Previously, the county was a distant contender, with odds of 250-to-1. Toronto (20-to-1) is the only city outside of the U.S. on the list.

In October, Paddy Power had Atlanta as the favorite to win the second Amazon(AMZN) headquarters.

At the time, it gave Atlanta odds of 2-to-1 on winning, ahead of Philadelphia (7-to-1), Boston (8-to-1) and Toronto (9-to-1).

Last year, the company received proposals from 238 cities and regions across 54 states, provinces, districts and territories in North America. Amazon said it will make a decision this year.

Many cities made elaborate gestures to attract the company's attention. For example, Tucson, Arizona sent Amazon CEO Jeff Bezos a giant 21-foot cactus, Birmingham, Alabama installed huge Amazon delivery boxes around town, and Kansas City Mayor James Sly gave 5-star reviews to an assortment of Amazon products. None of those cities made the short list.